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Retinoic acid decreases targeting of p27 for degradation via an N-myc-dependent decrease in p27 phosphorylation and

M Nakamura1, T Matsuo, J Stauffer

  • 1Cell and Molecular Biology Section, Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA.

Cell Death and Differentiation
|April 18, 2003
PubMed

Insights

Retinoic acid (RA) combats neuroblastoma (NB) by reducing N-myc and increasing p27 levels, halting cancer cell growth. RA achieves this through N-myc-dependent and -independent pathways, inhibiting p27 degradation.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Biology

Background:

  • Neuroblastoma (NB) prognosis is linked to N-myc amplification and overexpression.
  • Retinoic acid (RA) shows therapeutic potential by decreasing N-myc and inducing cell cycle arrest in NB.

Purpose of the Study:

  • To elucidate the mechanisms of RA-induced cell cycle regulation in NB.
  • To understand how N-myc influences NB cell cycle progression.

Main Methods:

  • Investigated the role of N-myc in regulating cyclin E-dependent kinase activity and p27 levels.
  • Assessed the impact of N-myc on p27 targeting to the proteasome and proteasome activity.
  • Examined RA's effects on N-myc levels, p27 degradation, phosphorylation, ubiquitination, and Skp2 levels.

Main Results:

  • N-myc overexpression increases cyclin E-dependent kinase activity, decreases p27, and enhances DNA synthesis.
  • N-myc promotes p27 degradation via phosphorylation and ubiquitination, increasing proteasome activity.
  • RA treatment reduces N-myc, increases p27, and decreases p27 degradation through both N-myc-dependent and -independent pathways, including reduced p27 phosphorylation and lower Skp2 levels.

Conclusions:

  • RA effectively arrests NB cell growth by stabilizing p27.
  • Both N-myc-dependent and -independent mechanisms contribute to RA's anti-neuroblastoma effects.
  • Targeting p27 stabilization presents a promising therapeutic strategy for neuroblastoma.

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